US2276107A - Gear pump - Google Patents

Description

Patented Mar. 10, 1942 2,276,107 GEAR PUMP John P. Simons, Lakew0od, Ohio.

Application May 9, 1939, Serial No. 272,626

4 Claims. (Cl. 103-126) This invention relates to the lubrication of rotary pumps employed to provide a constant pressure flow of fluid; forexample, gear pumps.

The construction of most gear pumps is such that any extraneous material used as a lubricant tends to work its way into the fluid which is being pumped. In cases where the lubricating material differs in its physical and/or chemical properties from the main body of fluid, the contamination that results is usually undesirable.

In some instances the physical properties; e. g., the.consistency, of the main body of fluid may be altered by the contaminating material to such an extent as to render it unfit for its intended use. On the other hand, certain lubricants affect the chemical nature of the main body of fluid, likewise destroying its usefulness for the purpose for which it is intended.

Contamination of the main body of fluid may in some cases be eliminated by using as a lubricant the material which is being passed through the pump. For instance, a pump used with fluids of low viscosity; e. g., an oil pump, may frequently be lubricated to advantage by part of the oil being pumped. In such case, because. of

its low viscosity, the fluid being passed through the pump can work its way into and around the surfaces to be lubricated. This principle may be employed in a great many cases where fluids of relatively low viscosity are handled, provided such fluids are otherwise capable of being used as lubricants.

An entirely different problem arises when gear pumps-are employed to pump fluids of comparatively high viscosity. In such a case, the fluid being pumped cannot be depended upon to work its way into the bearings; instead, the pump must be provided with pass-ages for conducting the lubricating materials to and from the moving p:rts, this in order to assure effective lubrication of the bearing surfaces. Usually, in such circumstances, the presence of pockets, dead air spaces, etc., in such passages tends to bring. about a more or less static condition of part of the I plate 'I are machined to provide fiuidetight joints fluid, thereby impairing but by no means destroying the effectivenessof the lubrication.

If, however, the fluid is one that tends to coag ulate, much more serious difliculties are encountered. A specific example is found in the lubri-. cat.on of the pumps employed in the production of viscose art'ficial silk thread. Viscose coagulates even when it is allowed to stand, but because of its thermal-sensitivity it coagulates still more readily if heat is applied. Therefore, if part of the viscose is employed as a lubricant, it

must be kept in motion so that neithera static condition of the fluid nor the heat of friction of the moving parts nor a combination of these two factors will cause the fluid to coagulate and 'bind the moving parts of the pump. Accordingly, in addition to providing passages for the lubricating medium, it becomes necessary to employ means providing a constant flow of lubricant through such passages. I The present invention provides a novel system of lubricating the movingparts of rotary pumps generally. Among other things, it provides'a system of lubrication adaptable to apparatus employed in pumping coagulable substances of relatively high viscosity; e. g., viscose. In substance, the invention provides a system of passages'through which part of the main body of I fluid which is passed into the pump is conducted to the bearing surfaces of the pump before beingreturned to or commingled with the body of fluid from which it was diverted. Thus the fluid being pumped cannot become contaminated by lubricants, but is itself utilized as a lubricant without involving any waste of fluid.

For purposes of illustration, but in no sense of limitation, the invention will be described hereinafter in connection with a gear pump of the type used in the manufacture of viscose artificial silk thread. I

In the accompanying drawing, Figure 1 represents a plan of a pump embodying the principle of' the present invention. Figure 2 represents an end elevation of the pump from line 22 of Figure 1. Figure 3 shows a sectional ele-' vation from line 3-3 of Figure 1. Figure 4 shows a sectional plan from line 4-4 of Figure 3. Figure 5 represents across section from line 5-5 of Figure 1. In the drawing, like reference characters refer to like parts throughout.

The pump illustrated as embodying the invention is made up of a support block I through which passes a rotary shaft 2; an intermediate plate 3 which fits against the face of support block I; a casing 4 embodying a pair of intermeshing gears 5 and 6, which casing fits against the opposite side of intermediate plate 3; and a cover plate 1 which fits against the opposite side of easing 4. The adjacent faces of support block I, intermediate plate 3, casing 4 and cover when the pump is assembled. Bolts 8, which pass through cover plate I, casing 4 and intermediate plate 3, are threaded into support block I to maintain the parts in assembled relationship,

.after which the pump as a 'whole is appropriately mounted by means of a bracket ,9 formed inte grally with support block I.

In the embodiment of the invention illustrated in the drawing, shaft 2, driven from a suitable power source, is rotatably carried by support block'l in a boss portion l3 formed therein. Shaft 2 extends through intermediate plate 3 into casing 4. Driving gear 5 is fixed to shaft 2, key 14 serving to maintain the parts in driving relationship, Meshing with driving gear 5 is an idler gear 8 mounted for free rotation about a partially hollowed stub shaft 15 which is tightly fitted in cover plate I and passes through a suitable bore in idler gear 6. Preferably, but by no means necessarily, the free end of stub shaft l abuts against the face of intermediate plate 3 adjacent casing l.

The fluid to be pumped is introduced into the interior of the pump through a suitable inlet passage ll formed inthe under portion of support block I and is passed out of the pump through a similar outlet passage l2 in the upper portion of support block I. An inlet chamber I! is provided in the casing l on one side of the point of mesh of the gears 5 and 8 and an outlet chamber I8 is provided in the casing on the opposite side of the point of mesh of said gears. As will appear, the pump as a whole, although involving the features of novelty hereinafter to be described, operates on theconventional principle with respect to the path of travel of the main body of fluid being pumped therethrough.

More specifically, an inlet conduit 18* which communicates with inlet passage ll passes through intermediate plate 3 to inlet chamber l7 formed on the intake side of casing 4. The fluid so admitted to casing 4 is carried from inlet chamber I! to the outlet chamber i8 on the opp'osite side of the casing in the spaces between the gear teeth. On the outlet side of casing d, the fluid passes out of the spaces between the gear teeth and into outlet chamber I8. Outlet chamber 18 communicates in turn with an outlet conduit l9 which communicates with outlet passage I2 formed in support block I.

A slightly lower pressure prevails in inlet chamtion I3, thereby providing lubrication for shaft 2 while passing through channel 22 to channel 23 ber I'l than in inlet passage I l and inlet conduit l8. This occurs by virtue of the fact that the gears Band 6 constantly remove the fluid from the inlet chamber I! to the outlet chamber it while the fluid is being supplied to inlet passage H by some external means as, for example, a pipe under superatmospheric pressure. In spite of the lower pressure which obtains in inlet chamber ll, the fluid forced into outlet chamber it cannot escape back into inlet chamber ii, there being no communicating passages between said inlet and outlet chambers, since gears 5 and d fit so closely in casing 4 as effectively to prevent any escape of the fluid around the periphery of the gears, whether between the gear teeth and the casing or between the faces of the gears and the intermediate or cover plate.

In order that suitable means may l'e provided for lubricating the various bearing surfaces as contemplated by this invention, the pump contains a first by-pass system including duct 24 and channels '22, 23 and 24. Duct 2! leads obliquely from inlet passage If to a bore in the boss 53 in which shaft 2 is mounted. A channel 22 in said bore in boss l3 extends from duct 2! adjacent to and longitudinally of shaft 2 disposed therein and provides for the passage of part of the main body of fluid therethrough. A channel 23 similar to and, in fact, a continuation of channel 22 is formed in intermediate plate 3 adjacent shaft 2 and communicates with another channel 24 which is also a continuation of the aforementioned channels 24 in the face of intermediate plate 3 adjacent one face of gear 5. Channel 2% lubricates the face of gear 5 which contacts intermediate plate 3. In order that the fluid thus used may be returned to the main body of fluid from which it was diverted, channel 243 termirelatively low pressure prevails. 1 Inasmuch as gear 6- rotates about stationary stub shaft l5, lubrication of both faces of gear nates in inlet chamber II, where, asstated, a

port 28 and. channels 29, 30 and 3|. Duct 25 leads obliquely from inlet passage ll through support block I to intermediate plate 3. A duct 26 formed in intermediate plate 3 issubstantially a continuation of and communicates with duct 25, terminating at the face of intermediate plate 3 adjacent stub shaft I 5. At the pointwhere the unsupported end of stub shaft [5 abuts against intermediate plate 3, the opening of duct 21 formed in stub shaft 15 coincides with theopening of duct 28 at the face of intermediate plate 3 and thereby constitutes a continuation of duct 28. A radial port 28 connects duct 21. 'o'f stub shaft I5 with a longitudinal channel 29 on the external surface thereof. At each endeof longi-' tudinal channel 29, channels 3! and 32 formed in .the faces of intermediate plate 3 and cover plate I adjacent gear 8 communicate with inlet chamber ll.

In operation, the main body of fluidpasses to the pump by way of inlet passage ii. The major portion of the main body of fluid passes through passage It to inlet chamber ll, while two comparatively small portions thereof are diverted from inlet passage H to provide lubrication of the various bearing surfaces'in thevpump. One of said portions of the main body of fluid passes from inlet passage H by way of said flrst by-pass system through duct 2! to channel 22 in-boss porin intermediate plate 3. Channel 24, also formed in intermediate plate 3 conducts this'portior. of the fluid along the surface of intermediate'plate 3 contacted by one face of gear 5, to inlet chamber l! where it is commingled with the main body of fluid. l

The other diverted portion of the main body of fluid passes from inlet passage H by way of said second by-pass system through duct 25 in support block I to duct 26 in intermediateplate 3 to the point where the hollowed duct 21 of stub shaft l5 communicates with duct 26. This portion of the fluid passes from duct 26 to duct 21 through radial port 28 to longitudinally extending channel 29 formed on the periphery of stub shaft IS. The fluid then passes through channel 29 to channels 3| and 32, providing lubrication for both faces of gear 6 and the surface of stub shaft i5 as the gear rotates thereabout. As part of the fluid from channel 29 passes through channel 3| it serves to lubricate the surface of intermediate plate 3 contacted by one face of gear 6. At the same time, the part of the fluid passing from channel '29 through channel 32 lubricates the surface of cover plate I in contact with the other face of gear 8. The fluid conducted through channels ti and 32 passes into inlet chamber II where it likewise commingles with the main body of fluid from which it was originally diverted.

Thus both diverted portions of fluid are comthe inlet chamber increases. Such pressure differential exists because of the removal of fluid from the inlet chamber and the flowing resistance .of the fluid which replaces such removed fluid.

According to the present invention, passages are provided to conduct the fluid being pumped from aipoint of higher relative pressure through the parts to be lubricated to a point of lower relative pressure, so that such pressure differential produces a flow. of the fluid being pumped for a lubricating purposes; 1

The. system describedconstitutes a particularly the point remote from the zone of engagement of emcient system of lubricating gear pumps, espe-- cially'gear pumps of thetype illustrated. The utilization of the hollowed portion of the stub shaft as a lubricating channel enables the system to function to particular advantage.

spaces are eliminated, lubricant being delivered in suflicient quantity and with sufficient movement to prevent any coagulation of the fluid being pumped therethrough Further, the system provided by the invention precludes the possibility of contamination of the main body of fluid by the lubricant, inasmuch asv the lubricant comprises the material being passed through the main body of the pump.

By "means of this feature of the invention, all static It is not to be inferred that the invention cannot be applied to forms of pumps other than that illustrated. Nor is it intended that the scope of the invention should be limitedto the apparatus shown in the drawing. Various modifications of the illustrated embodiment of the invention may be made without departing from the spirit of the invention. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

What isclaimed is:

1. A rotary pump comprising two inter-meshing fluid-impelling gears; an enclosure in which said gears flt closely including surfaces in-consaid gears being spaced from the point in proximity thereto so that the pressure differential between said points is sumcient toassist flow of fluid from said remote point to said supporting means, thence from said supporting means forlubrication of said supporting means.

Ii. A rotary pump comprising a driving gear; an idler gear having a central bore, 'said idler gear meshing with said drivinggear; an enclosure in which said gears flt closely including surfaces in contact with the faces of said gears; a ffluid inlet passage leading to said enclosure on one side of the zone of engagement of said gears; a fluid outlet passage leading from said enclosure on the opposite side of ,the zone of engagement of said gears; supportingmeans about which said idler gear rotates in said enclosure, said means passing through the bore in said idler gear; and

a fluid by-pass system including lubricating channels adjacent the surfaces contacted by the faces and bore of said idler gear operative to conduct a portion of the main body'of fluid from said inlet passage at a point remote from the zone of engagement of said gears. at which point the pressure of the fluid to be pumped is greater than at the inlet side of-the zone of engagement of the gears, to the faces and bore of said idler gear and to return said portion of fluid to the main body thereof at a point less remote from said zone of engagement of said gears than the point at which" it was taken from the main body, the

tact with the faces of said gears; an inlet passage" in said enclosure through which fluid to be pumped is supplied to said fluid-impelling gears;

an outlet passage in said enclosure through which said fluid passes from said pump; and a fluid by pass system in said enclosure including means operative to conduct continuously a portion of the incoming fluid from a'point in said inlet passage remote from saidgears, at which point the pressure of the fluid-to be pumped is greaterthan that at the intake side of the zone of engagement of the gears, to the surfaces in contact with both faces of at least-one of said-gears and space between such points being such that the pressure differential therebetween is sufllcient to assist flow of fluid through said lubricating chanengagement of said gears.

' nels from said remote point toward the zone of *4. A rotary pump comprising a driving gear; an idlergear having a central bore, said idler gear meshing with said driving gear; an enclosure in which said gears flt closely including surfaces in contact with the faces and the bore of to return the by-passed fluid to'the incoming.

fluid at a point spaced nearer thezone of engagement of said gears than said first-mentioned point at least by an amount such that the pressure differential between said points is suflicient to assist flow of fluid through said by-pass system to the surfaces contacted, by the faces of said gears and back to the incoming fluid.

2. A-rotary pump comprising adriving gear; an idler gear meshing with said driving gear; an enclosure in which said gears flt closely ineluding a fluid inlet passage-and a fluid outlet passage; supporting a means in said enclosure about which said idler gear rotates; and afluid by-pass system including means operative to con-- duct continuously a portion of the incoming fluid fromapoint rr e mote from said gears, at which said idler gear, an inlet passage and an outlet passage; supporting means in said enclosure about which'said idler gear rotates, said means passing through the bore in said idler gear; and a fluid by-pass system including lubricating channels disposed adjacent both faces of said idler gear and a lubricating channel disposed on the surface of said supporting means, said bypass system including means operative to lubri.-' cate the faces and bore of said idle'r gear by conducting a portion of the incoming fluid from said inlet passage at a point remote from the zone of engagement of said gears, through said lubricating channels to a point lessremotefromthe 'zone of'engagement of said gears than said flrst-mentioned'point, the distance between said points being such that the pressure differential in the inlet passage is sufflcient to assist flow of the fluidtoward the zone of engagement of said gears from said remote point in said inlet passage, through the by -pass system to the faces and bore of said idler gear and back to said incoming fluid. 3

JOHN P. SIMQNSQ

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